Broadcast of television signals via cable distribution systems has been provided for a number of years. The number of channels transmitted has continued to increase over time. In recent years, the need for transmission bandwidth in the networks has not only been due to increasing television channel availability, but has also been driven by new technologies and uses. For example, broadband data transmission for transferring large amounts of information between computer systems, such as through the use of cable modems, has become common. Additionally, services such as digital voice transmission (e.g., voice over Internet protocol (VoIP)) have gained widespread acceptance, and thus create additional demand on network transmission bandwidth. Likewise, services such as video on demand have created additional demand for network transmission bandwidth.
Accordingly, network operators have periodically replaced network infrastructure (e.g., modulators, transmission cables, splitters, amplifiers, etc.) and subscribers have replaced subscriber equipment (e.g., set-top boxes, television sets, etc.) to accommodate the transmission and reception of increased numbers of channels. For example, in order to provide transmission of increasing numbers of channels cable networks have progressed through 330 MHz transmission bandwidth, 550 MHz transmission bandwidth, 750 MHz transmission bandwidth, to 870 MHz transmission bandwidth. Some cable networks presently provide as much as 1 GHz transmission bandwidth.
Replacing network infrastructure is time consuming and costly. Accordingly, network operators are often reluctant to make changes in order to provide increased transmission bandwidth. Moreover, the time and cost associated with upgrading network infrastructure is generally not the greatest impediment to implementing increased transmission bandwidth. Network infrastructure generally serves multiple subscribers, such as on the order of one device serving 32-1000 subscribers in many cases. However, subscriber equipment, such as set-top boxes or television tuners, serve a single subscriber. Therefore, network transmission bandwidth increases which implicate subscriber equipment is even more time consuming and costly than replacing network infrastructure. That is, each individual piece of subscriber equipment would require replacement or upgrading in order to implement the network transmission bandwidth increase.
At least in part for the foregoing reasons, network operators have been reluctant to implement network transmission bandwidth increases beyond 1 GHz. Instead of implementing transmission bandwidth increases, many network operators have implemented techniques for providing increased data throughput via the same network transmission bandwidth. For example, analog television channels, which previously each required 6 MHz bandwidth radio frequency (RF) channels for transmission, have been digitally encoded and compressed such that a single 6 MHz bandwidth RF channel carries a plurality of logical channels (e.g., 10 of the foregoing digitized and compressed television channels). Likewise, some network operators have implemented switched digital video (SDV) systems wherein on the RF (e.g., television) channels containing programming currently requested or in use by subscribers within a particular transmitter's service area are transported over that particular transmitter, to thereby utilize network bandwidth more efficiently.